Shaft retaining means for hydrostatic steering devices

ABSTRACT

A structure for retaining the steering shaft of a hydrostatic steering device in the same operative axial position irrespective of the number of adjusting shims employed to operatively position the valve member actuated by the shaft, or the presence or absence of pressure in the hydraulic system of the device and which is so constructed that no restraining forces on the shaft tending to produce relatively high frictional forces and causing high steering torques are produced.

United States Patent [191 Miller Oct. 23, 1973 SHAFT RETAINING MEANS FORHYDROSTATIC STEERING DEVICES [75 Inventor: Laurence L. Miller, WestLafayette,

Ind. [7 31 A si TBW,Im-IQ d ndLQhiQ.

[22] Filed: July 5, 1972 [21] Appl. No.: 269,161

[52] U.S. Cl 251/213, 137/625.24, 308/234 [51] Int. Cl. Fl6k 31/44 [58]Field of Search 91/368, 382, 375;

[56] References Cited UNITED STATES PATENTS Elwell 137/6252] Pitner308/234 X Lubos 418/61 X Goff et al 418/61 Primary Examiner-Henry T.Klinksiek Attorney-Benjamin H. Sherman et al.

[57] ABSTRACT A structure for retaining the steering shaft of ahydrostatic steering device in the same operative axial positionirrespective of the number of adjusting shims employed to operativelyposition the valve member actuated by the shaft, or the presence orabsence of pressure in the hydraulic system of the device and which isso constructed that no restraining forces on the shaft tending toproduce relatively high frictional forces and causing high steeringtorques are produced.

14 Claims, 4 Drawing Figures SHAFT RETAINING MEANS FOR HYDROSTATICSTEERING DEVICES BACKGROUND OF THE INVENTION The invention is directedgenerally to hydrostatic steering devices and more particularly to anovel retaining structure which prevents undesired axial movement of theoperating or actuating shaft thereof under all positions of axial shaftadjustment and varying operational hydraulic conditions.

Illustrations of the general type of steering devices here involved areillustrated, for example, in US. Pat. No. 3,452,543, granted July 1,1969 to R. L. Goff et al. and No. 3,597,128, granted on Aug. 3,'l97l toFredrich D. Veneable et al. I

Steering devices of the type here involved employ a rotatable actuatingshaft, for example, adapted to be actuated by a steering wheel 'mountedthereon, which is operative to control the movement of a metering spoolvalve member, the operational positioning of which determined thehydraulic operation of the'structure. As the operative positioning ofthe spool. valve member must be quite exact, irrespective ofmanufacturing tolerances in the components of the assembly, structureshave been designed to accommodate suitable adjusting shims, operative toaccurately'position the shaft and therewith the spool valve member.However, in many cases the shims are basically operative in only onedirection, i.e under the action of fluid pressure within the hydraulicsystem whereby the actuating shaft may be adequately retained in anaxially fixed position in the presence of hydraulic pressure but capableof an amount of axial retraction in the absence of such hydraulicpressure. An undesirable amount of axial play is thus introduced intothe structure, for'exampl e, in situations prior to operation ofthevehicle engine or in the event the vehicle is steered without the engineoperating. Under such conditions the steering shaft can be moved in andout of the steering device with a small amount of force, and as theshaft will normally be retracted when the device is inoperative, uponstarting the engine the increased fluid pressure inside the steeringdevice will cause a corresponding extension of the shaft to its normaloperating position. The cost to fabricate a single spacing member to theexact length re quired to accommodate the particular number of shimsemployed in any given assembly is prohibitive.

The present invention is therefore directed to a shaft assembly which ismaintained in axially fixed relation irrespective of the operativecondition of the device and which will not introduce undesiredoperational characteristics in the actuation of the shaft and thus theoperation of the device, and which enables accurate positioning of thespool valve member.

BRIEF SUMMARY OF THE INVENTION The problem presented is solved in thepresent invention by the utilization of a suitable bearing assemblywhich is carried by the actuating shaft in an operationally axiallyfixed relation, provision being made to provide an adjustment, forexample, by means of suitable shims, in the position of the bearingassembly relative to the stationary housing of the device, tooperatively axially position the actuating shaft and thereby accuratelyposition the controlling spool valve member, relative to its cooperablevalve body, for the desired operation. Resilient means is provided foraccommodating the operational thickness range of adjustment shims, andat the same time operatively retain the parts in the desired axialposition irrespective of the presence and absence of pressure in thehydraulic system.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERREDEMBODIMENT Hydrostatic steering devices of the type illustrated in thereference patents generally include a fluid controller for regulatingthe flow of pressurized fluid to a hydraulically operated device andincludes in a single casing a gear set which may serve as a fluid meter,in cooperation with an axially shiftable spool valve for controlling theflow of fluid through the gear set and to a hydraulically operateddevice. A control or actuating shaft is rotatably mounted on the casingin axial alignment with the spool valve and is coupled to the valve sothat rotation of the control shaft in opposite directions causes thespool valve to shift axially in opposite directions from a neutralposition to axially spaced operating positions.

The coupling between the control shaft and the spool valve may comprisea cooperating helical groove and ball arrangement, and further maycomprise means to provide joint rotation between the shaft and the valvebut to permit some limited relative rotation therebetween. I

Referring to the drawings, and particularly to FIG. 1, the referencenumeral 1 designates generally a housing structure which, in theconstruction illustrated, comprises a main section 2, and a smaller endsection 3,

suitably secured to the section 2. Rotatably mounted in the housing 1 isan actuating or control shaft 4 (which may, for example, carry asteering wheel) having an axis of rotation which coincides with alongitudinal axis of the housing 1, with the free end of theshaft'extending through the section 3, aNd connected therewith bysuitable roller bearings 5, with the free end of the shaft beingsuitably sealed by respective sealing and retaining rings designatedgenerally by the numeral 6.

The housing section 2 is provided with an axially extending bore 7therein provided with a plurality of ports 8, cooperable with a controlvalve member, herein termed a spool valve member which is cooperablycoupled to the shaft 4 by means of a ball 10, seated in a cooperablerecess in the valve member 9, and riding in a cooperable helical groove11 in the periphery of the shaft 14. The latter also may be providedwith a radially extending stud (not illustrated) carried by the shaftand having an outer portion disposed in an axially extending slot in thevalve member 9, the longitudinal sides of the slot being spacedcircumferentially a distance greater than the cooperable portion of thestud to permit a desired amount of relative rotation between the shaftand the valve member, with relative axial movement between the shaft andvalve member being determined by the configuration of the helical groove11. Thus, the valve member may have both axial and rotative movementrelative to the shaft 4.

As the other details of the hydrostatic steering device form no part ofthe present invention and various forms of construction may be employedtherein, further description of other illustrated parts of the device isdeemed unnecessary to a full understanding of the present invention.

The embodiment of the invention illustrated includes a bearing assemblyindicated generally by the numeral 12, comprising a pair of bearingraces 13 and 14 between which is disposed a needle bearing 15comprising, for example, a plurality of needle bearings and suitableseparator therefor, the race 13 disposed adjacent the spool valve member9, being termed the inner race and the race 14 being termed the outerrace.

As will be apparent from a reference to FIGS. 1 and 2, the inner race 13has a lesser outer diameter than the race 14 and is adapted to axiallyseat on a shoulder or abutment 16 formed on the shaft 4, whereby axialforces in a direction toward the free end of the shaft 4 are transmittedto the race 13. The bearing assembly 12 is retained in operative axialposition on the shaft 4 by a retaining ring of the split type having itsinner edge portions seated in a cooperable groove 18 formed in the shaft4. The axial distance between the abutment l6 and the retaining ring 17,with respect to the corresponding dimensions of the bearing assembly issuch that the latter is relatively snugly retained in axial position onthe shaft 4 without undesired prestressing of the bearing.

As illustrated in FIG. 2, the split retaining ring 17 is provided with atwist between the opposite leg portions 17a and 17b thereof with suchtwist taking place through an arc 170 not greater than 30 to each sideof the diametrical centerline passing between the free ends of the twoleg portions. With such construction the retaining ring, when seated inthe groove 18, will be firmly and, for operational purposes, rigidlysecured to the shaft with any axial play between the ring and shaftbeing eliminated. Consequently, with this construction the bearingassembly 12 may be considered as carried on the shaft 4 in axially fixedrelation.

The bearing assembly 12 and thus the shaft 4, and thereby theoperational axial positioning of the spool valve member 9 with respectto the ports 8, is adjusted and determined by shims 19 which aredisposed concentrically with the retaining ring 17 and interposedbetween the adjacent outer face of the bearing race 14 and the abutment20, formed as a radially extending face on the end section 3. Thus, byvarying the number of shims and possibly the thickness of the shims theassembly including the bearing assembly 12, shaft 4 and spool valvemember 9 may be axially adjusted to position the spool valve member 9 inaccurate desired operational relationship with respect to the ports 8 inthe housing.

It will be particularly noted that pressure in the hydraulic systemduring the operation of the device will firmly retain the shaft assemblydescribed in its outermost position, i.e., to the right as viewed inFIG. 1. Inward or retracting movement of the shaft 4 in the absence ofpressure in the system is prevented by a sleeve member 21 disposedwithin the housing section 2 and seated at its inner end on the adjacentend face of such section, in cooperation with an annular wave spring 22.

The spring 22 is disposed substantially concentric with the needlebearings 15, and is axially interposed between the adjacent end of thesleeve member 21 and the radially outer portion of the inner face of therace member 14.

It will be apparent that in this construction the outer race member 14is maintained in firm, fixed engagement, at all times, with the shims19, as the wave spring 22 is constructed to provide sufficientresiliency to permit its compression when the number and size of theshims 19 provide maximum thickness and at the same time providesufficient expansion forces acting on the bearing race 14, when thethickness of the shims is at a minimum, to insure a firm retention ofthe bearing race 14, and with it the bearing assembly 12 and shaft 4, intheir normal positions even in the absence of pressure in the hydraulicsystem and the presence of normal manual loads applied to the shaft inaxially inward direction.

Under normal manufacturing tolerances, the number of shims required tosuitably position the valve spool member will vary by approximately0.100 inches. Consequently, a single wave spring washer and tubularspacer sleeve areadequate to retain the shaft and associated parts inthe desired fixed axial position relative to the supporting member,irrespective of the particular number of shims employed, to provide thedesired positioning of the valve spool.

It will be particularly noted from the above, that the construction issuch that the retaining assembly introduces no undue frictional forcesbetween the shaft and the housing irrespective of the number of shimsemployed, and at the same time the shaft is retained in an axially fixedposition with respect to the housing and the spool valve accuratelypositioned with respect to the cooperable valve ports, etc.

Although minor modifications might be suggested by those versed in theart, it should be understood that I wish to embody within the scope ofthe patent warranted hereon all such modifications as reasonably cornewithin the scope of my contribution to the art.

We claim as our invention:

1. In a hydrostatic steering device having a hydraulic power systemwhich includes a stationary valve body, a shaft rotatable in the bodyand a valve member movable in predetermined relation relative to saidshaft, the combination of a bearing assembly disposed on said shaft,means on said shaft for supporting said assembly thereon insubstantially fixed axial relation and operative to transmit hydraulicpressure, acting on said shaft in axial direction, to said bearingassembly, at least one shim member disposed between the outermost faceof said bearing assembly and an adjacent opposed fixed abutment,operative to axially so position said bearing assembly and shaft thatthe valve member will be disposed in predetermined operative axialalignment with the stationary valve body in the presence of pressure inthe hydraulic system, and resilient means bearing upon a relativelystationary portion of said bearing assembly and arranged to exertpressure thereon in the direction of said shim to operationally retainsaid assembly in engagement therewith whereby said shaft issubstantially axially fixed relative to said body in the presence orabsence of pressure in the hydraulic system.

2. A device according to claim 1 wherein said resilient means compriseswave spring washer.

3. A device according to claim 1 wherein said bearing assembly comprisesan inner race of relatively small outer diameter, an outer race ofrelatively large outer diameter, and antifriction means disposedtherebetween having an outer diameter less than that of said outerportion of said outer race, said resilient means bearing on the radiallyouter portion of said outer race and operative to operationally retainthe same in engagmenet with said shim.

4. A device according to claim 3, wherein said anti.- friction meanscomprises a plurality of needle bearings and suitable separatortherefor.

5. A device according to claim 1 comprising in further combination, acylindrical sleeve encircling said shaft and having its relatively innerend seated on an axially fixed abutment, the opposite end of said sleeveforming an abutment with which the adjacent portion of said resilientmeans is engaged.

6. A device according to claim 5 wherein said resilient means comprisesa wave spring washer.

7. A device according to claim 1 wherein said bearing retaining means onsaid shaft comprises an abutment for transmitting axially directedpressure on said shaft to said bearing assembly, and a split retainingring seated in a groove in said shaft at the opposite side of saidassembly.

8. A device according to claim 7 wherein said split retaining ring is ofgenerally U-shaped configuration and has a preset twist therein locatedat the intermediate portion thereof.

9. A device according to claim 8 wherein said preset twist extends fornot more than 30 at each side of a diametrical line extending betweenthe free ends of the leg portions of said U-shaped configuration.

10. A device according to claim 9 wherein the preset twist in saidretaining ring is such that the load exerted thereby, after beingcompressed solid, does not exceed 20 lbs. when restrained between twoparallel surfaces spaced approximately 0.05 inches and more than 8 lbs.when restrained between two parallel surfaces spaced approximately 0.06inches.

11. A device according to claim 8 wherein said bearing assemblycomprises an inner race of relatively small outer diameter, an outerrace of relatively large outer diameter, and antifriction means disposedtherebetween having an outer diameter less than that of said outerportion of said outer race said resilient means bearing on the radiallyouter portion of said outer race and operative to operationally retainthe same in'engagement with said shim.

12. A device according to claim 11, wherein said antifriction meanscomprises a plurality of needle bearings and suitable separatortherefor.

13. A device according to claim 12 comprising in further combination, acylindrical sleeve encircling said shaft and having its relatively innerend seated on an axially fixed abutment, the opposite end of said sleeveforming an abutment with which the adjacent portion of sald resilientmeans is engaged.

14. A device according to claim 13 wherein said resilient meanscomprises a wave spring washer.

1. In a hydrostatic steering device having a hydraulic power systemwhich includes a stationary valve body, a shaft rotatable in the bodyand a valve member movable in predetermined relation relative to saidshaft, the combination of a bearing assembly disposed on said shaft,means on said shaft for supporting said assembly thereon insubstantially fixed axial relation and operative to transmit hydraulicpressure, acting on said shaft in axial direction, to said bearingassembly, at least one shim member disposed between the outermost faceof said bearing assembly and an adjacent opposed fixed abutment,operative to axially so position said bearing assembly and shaft thatthe valve member will be disposed in predetermined operative axialalignment with the stationary valve body in the presence of pressure inthe hydraulic system, and resilient means bearing upon a relativelystationary portion of said bearing assembly and arranged to exertpressure thereon in the direction of said shim to operationally retainsaid assembly in engagement therewith whereby said shaft issubstantially axially fixed relative to said body in the presence orabsence of pressure in the hydraulic system.
 2. A device according toclaim 1 wherein said resilient means comprises wave spring washer.
 3. Adevice according to claim 1 wherein said bearing assembly comprises aninner race of relatively small outer diameter, an outer race ofrelatively large outer diameter, and antifriction means disposedtherebetween having an outer diameter less than that of said outerportion of said outer race, said resilient means bearing on the radiallyouter portion of said outer race and operative to operationally retainthe same in engagmenet with said shim.
 4. A device according to claim 3,wherein said antifriction means comprises a plurality of needle bearingsand suitable separator therefor.
 5. A device according to claim 1comprising in further combination, a cylindrical sleeve encircling saidshaft and having its relatively inner end seated on an axially fixedabutment, the opposite end of said sleeve forming an abutment with whichthe adjacent portion of said resilient means is engaged.
 6. A deviceaccording to claim 5 wherein said resilient means comprises a wavespring washer.
 7. A device according to claim 1 wherein said bearingretaining means on said shaft comprises an abutment for transmittingaxially directed pressure on said shaft to said bearing assembly, and asplit retaining ring seated in a groove in said shaft at the oppositeside of said assembly.
 8. A device according to claim 7 wherein saidsplit retaining ring is of generally U-shaped configuration and has Apreset twist therein located at the intermediate portion thereof.
 9. Adevice according to claim 8 wherein said preset twist extends for notmore than 30* at each side of a diametrical line extending between thefree ends of the leg portions of said U-shaped configuration.
 10. Adevice according to claim 9 wherein the preset twist in said retainingring is such that the load exerted thereby, after being compressedsolid, does not exceed 20 lbs. when restrained between two parallelsurfaces spaced approximately 0.05 inches and more than 8 lbs. whenrestrained between two parallel surfaces spaced approximately 0.06inches.
 11. A device according to claim 8 wherein said bearing assemblycomprises an inner race of relatively small outer diameter, an outerrace of relatively large outer diameter, and antifriction means disposedtherebetween having an outer diameter less than that of said outerportion of said outer race said resilient means bearing on the radiallyouter portion of said outer race and operative to operationally retainthe same in engagement with said shim.
 12. A device according to claim11, wherein said antifriction means comprises a plurality of needlebearings and suitable separator therefor.
 13. A device according toclaim 12 comprising in further combination, a cylindrical sleeveencircling said shaft and having its relatively inner end seated on anaxially fixed abutment, the opposite end of said sleeve forming anabutment with which the adjacent portion of saId resilient means isengaged.
 14. A device according to claim 13 wherein said resilient meanscomprises a wave spring washer.